Articles having an odor control system comprising a cationic polysaccharide and an odor controlling agent

ABSTRACT

The present invention relates to articles suitable for controlling odors, especially odors associated with bodily fluids, which comprise a cationic polysaccharide, preferably chitosan material, together with an odor controlling agent, preferably an odor absorbent agent and/or a chelating agent. This combination provides synergistic reduced odor control towards malodors associated with bodily fluids like menses.

CROSS REFERENCE TO RELATED REFERENCES

This is a continuation of International Application PCT/US01/13159 withan International filing date of Apr. 24, 2001.

FIELD OF THE INVENTION

This invention relates to articles, such as absorbent articles, forcontrolling odors, especially odors associated with bodily fluids,comprising a cationic polysaccharide, preferably chitosan material,together with an odor-controlling agent.

BACKGROUND OF THE INVENTION

Malodors may be present in the environment from numerous sources bothanimate and inanimate. Many products and articles are available whichaim to avoid or minimize the detection of such odors. In particular, itis particularly desirable to provide odor controlling materials toaddress the malodors which are generated by the human body, or frombodily fluids such as perspiration, urine, faeces, menstrual fluids,vaginal fluids and the like.

Articles like absorbent articles for example are designed to be worn byhumans to absorb bodily fluids, such as urine, menstrual fluid andperspiration, etc. Examples of absorbent articles include sanitarynapkins, pantiliners, disposable diapers, incontinence pads, tampons,perspiration pads, nursing pads and the like.

In use, the absorbent articles are known to acquire a variety ofcompounds, for example volatile fatty acids (e.g. isovaleric acid),ammonia, amines (e.g. triethylamine), sulphur containing compounds (e.g.mercaptans, sulphides), alcohols, ketones and aldehydes (e.g.,furaldehyde) which release unpleasant odors. These compounds may bepresent in the bodily fluid or may be developed by chemical reactionsand/or any fluid degradation mechanisms once the bodily fluid isabsorbed into the absorbent article like for example a feminine pad. Inaddition bodily fluids usually contain micro-organisms and/or enzymesthat can also generate malodorous by products as a result of degradationmechanisms like putrefactive degradation, acid degradation, proteinsdegradation, fat degradation and the like. Unpleasant odors, whichemanate from absorbent pads when in use, may make the wearer feelself-conscious.

Various odor-controlling materials have been disclosed in the art tocombat some of the unpleasant odors referred to above. Indeed solutionshave been provided that use different technical approaches like masking,i.e., covering the odor with a perfume, or absorbing the odor alreadypresent in the bodily fluids and those generated after degradation.

Most of the focus in the prior art is found on the odor absorptiontechnology. Examples of these types of compounds include activatedcarbons, clays, zeolites, silicates, starches, cyclodextrine, ionexchange resins and various mixture thereof as for example described inEP-A-348 978, EP-A-510 619, WO 91/12029, WO 91/11977, WO 89/02698,and/or WO 91/12030. All of these types of odor controlling agents arebelieved to control odor by mechanisms whereby the malodorous compoundsand their precursors are physically absorbed by the agents and thus suchagents hinder the exit of the odor from articles like absorbentarticles. However, such mechanisms are not completely effective as theformation of the odor itself is not prevented and thus odor detection isnot completely avoided.

Thus although these materials provide some control of odors associatedwith bodily fluids, there still exists a need of further improvement interms of odor control over a wide range of malodorous compounds.

It is an object of the present invention to provide effective odorcontrol over a wide range of malodors. More particularly, it is anobject of the present invention to provide articles, especiallydisposable absorbent articles, which deliver outstanding odor controlover a broad spectrum of malodors.

It has now been found that the above needs can be addressed by combininga cationic polysaccharide together with an odor-controlling agent, asthe odor control system for an article, preferably a disposableabsorbent article.

It has surprisingly been found that the combination of an odorcontrolling agent, typically an odor absorbent agent (e.g., zeoliteand/or cyclodextrin) and/or a chelating agent (e.g., ethylene diaminetetracetate (EDTA)) together with a cationic polysaccharide, preferablychitosan material, in an article, like an absorbent article, typicallycoming into contact with bodily fluids, results in a synergistic effectin terms of odor control. Indeed this combination gives more odorreduction than the odor reduction associated with the use of one ofthese two classes of ingredients alone at the same total level (eithersaid odor controlling agent alone or said cationic polysaccharide alone)in an absorbent article contacted with bodily fluids.

Actually the combination of a cationic polysaccharide with anodor-controlling agent in an article herein allows combining odorcontrol mechanisms by which the overall malodor detection issynergistically reduced or even prevented.

Without to be bound by any theory it is believed that cationicpolysaccharides, preferably chitosan materials, provide odor control ofmalodorous components associated with bodily fluid by multiplemechanisms.

Firstly, the odor absorption and retention characteristics ofpolysaccharides are due to the presence in the polymer structure ofionisable cationic functional groups. These groups are usually ammoniumgroups, a high proportion of which are in the salt form when the polymeris dry but which undergo dissociation and salvation upon contact withbodily fluid. In the dissociated state, the polymer chain will have aseries of functional groups attached to it which groups have the sameelectric charge (e.g., —NH₃ ⁺ ⁺H₃N—) and thus repel one another. Thisleads to expansion of the polymer structure, which, in turn permitsfurther absorption of negatively charged odorous molecules and thus thecontrol thereof.

Secondly, the positively charged cationic groups of the polysaccharideswill interact with negatively charged anionic functionalities present inbodily fluids, like the carboxylic groups of proteins or hydroxylic acidbearing entities like short chain acid (e.g., butyric acid). This willresult in the formation of tri-dimensional net between cationicpolysaccharides and such molecules with anionic groups (gelification ofthe bodily fluids). This gelification will entrap most odorous molecules(like lipids, acids) thereby controlling malodor.

Thirdly and more importantly the cationic polysaccharides especially theaminopolysaccharides (chitosan materials) are believed to act asantimicrobial agents. Indeed the polysaccharides with their positivelycharged cationic groups will interfere with negatively charged surfaceof microorganism walls, thereby inhibiting the growth of suchmicroorganisms or even killing such microorganisms. These cationicpolysaccharides will also interfere with negatively charged surface ofenzymes, thereby inactivating the enzymatic activity, which, like themicrobial activity, are otherwise responsible for the formation ofmalodorous components. The cationic polysaccharides like chitosanmaterials further act by their indirect antimicrobial activity bylinking some of the microorganism nutriments like lipids and/orminerals.

Surprisingly, the presence of the cationic polysaccharide, like chitosanmaterial, increases the effectiveness of odor controlling agents likeodor absorbent agents. Without to be bound by any theory it isspeculated that the cationic polysaccharides herein, typically chitosanmaterials, control enzymatic and microbial growth and as a consequencethe amount of malodorous compounds associated with the enzymatic andmicrobial activity occurring in bodily fluid. In other words, thecationic polysaccharides reduce or even prevent the formation ofmalodorous compounds, thereby reducing the total amount of malodor to becontrolled. This allows the odor-controlling agent, typically the odorabsorbent agent (e.g., zeolite and/or cyclodextrin) to work in reducedamount of active. Actually this results in a more effective as well as asustained use of the odor-controlling agent herein. Indeed thesaturation point of the odor absorbent agents when used in associationwith the cationic polysaccharides herein will be reached after prolongedperiods of use, typically after prolonged wearing time of an absorbentarticle (pantiliner, pad) coming into contact with bodily fluid, ascompared to when used alone in absence of the cationic polysaccharidesin the same conditions.

Advantageously it is believed that the odor controlling agents,typically the odor absorbent agents, also help the cationicpolysaccharides in reducing malodor by adsorbing not only odor presentin the bodily fluids but also volatile odor present in the head space(space between the absorbent article and the urogenital surface). Thiscombination is thus active too towards volatile malodor components,which escape from the bodily fluids and hence would not come in directcontact with the polysaccharides. Actually this combination allows odorcontrol over a wider range of malodorous components, which wouldotherwise not have been fully controlled by one of these two classes ofingredients used alone.

Surprisingly the presence of a chelating agent on top of the cationicpolysaccharide, namely chitosan material, results in increasedantimicrobial properties. Without to be bound by any theory it isbelieved that the chelating agents used herein complete theantimicrobial properties of the cationic polysaccharides, by theirindirect antimicrobial activity. Indeed the chelating agents have theability to link some of the microorganisms nutriments like positivelycharged growth factors, typically Ca⁺⁺, K⁺, Mg⁺⁺. Advantageously thecombination of these two preventing mechanisms results in a synergisticreduction in odor formation.

In a preferred embodiment herein the disposable absorbent articles havean apertured polymeric film topsheet. This topsheet contributes tofurther improve the odor control benefit.

In another preferred embodiment herein the disposable absorbent articleshave a breathable backsheet. This contributes to a further improved odorcontrol benefit. Even more preferred herein the disposable absorbentarticles have both a breathable backsheet and an apertured polymericfilm topsheet.

The present invention is preferably directed to disposable absorbentarticles like pantiliners, feminine napkins, incontinent pads, diapers,tampons, interlabial pads, perspiration pads, surgical pads, breastpads, human or animal waste management devices and the like. Otherarticles suitable for use according to the present invention furtherinclude articles designed to be contacted with the body such asclothing, bandages, thermal pads, acne pads, cold pads, compresses,surgical pads/dressings and the like, body cleansing articles likeimpregnated wipes/tissues (e.g. baby wipes, wipes for feminine intimatehygiene), articles for absorbing perspiration such as shoe insoles,shirt inserts, and the like, and articles for animals like litters andthe like.

BACKGROUND ART OF THE INVENTION

WO 99/61079 discloses odor reduction for products such as disposablediapers and training pants, sanitary napkins and tampons by the use oftriglycerides and polyglycosides to enhance the malodor absorptionproperties of compositions and substrates such as naturally occurringpolymers like chitosan or alginates and synthetic polymers treated withsurfactants.

WO 99/32697 discloses that chitosan and chitin-based polymers exhibitincreased antimicrobial activity when coated onto the surface of ahydrophobic material such as polypropylene.

None of these references discloses absorbent articles comprisingcationic polysaccharides, typically chitosan materials, together with anadditional odor controlling agent, typically an odor absorbent agentlike zeolite and/or cyclodextrin, or a chelating agent like ethylenediamine tetracetate, let alone that such combinations result insynergistic malodor reduction.

SUMMARY OF THE INVENTION

The present invention relates to an article, preferably a disposableabsorbent article, for controlling odors, preferably odors associatedwith bodily fluids, comprising a cationic polysaccharide and anadditional odor-controlling agent. In a preferred embodiment of theinvention the article also comprises an absorbent gelling material.

DETAILED DESCRIPTION OF THE INVENTION

By “article” it is meant herein any three-dimensional solid materialbeing able to comprise a cationic polysaccharide and an odor-controllingagent. The term “disposable” is used herein to describe articles, whichare not intended to be launched or otherwise restored or reused as anarticle (i.e., they are intended to be discarded after a single use and,preferably to be recycled, composted or otherwise disposed of in anenvironmentally compatible manner). The term “absorbent articles” isused herein in a very broad sense including any article able to receiveand/or absorb and/or contain and/or retain fluids and/or exudates,especially bodily fluids and/or exudates.

Preferred articles according to the present invention are disposableabsorbent articles that are designed to be worn in contact with the bodyof a user and to receive fluids/exudates from the body, such aspantiliners, sanitary napkins, catamenials, incontinence inserts/pads,diapers, tampons, interlabial pads/inserts, breast pads, human or animalwaste management devices and the like. Typically such human urine orfaecal management devices comprise a bag having an aperture and a flangesurrounding the aperture for preferably adhesive attachment to theurogenital area and/or the perianal area of a wearer. Any faecal orurine management device known in the art is suitable for use herein.Such devices are described in for example WO 99/00084 to WO 99/00092.Other suitable articles according to the present invention also includeother articles designed to be placed against or in proximity to the bodysuch as clothing, bandages, thermal pads, acne pads, cold pads,compresses, surgical pads/dressings and the like, articles for absorbingperspiration such as shoe insoles, shirt inserts, perspiration pads andthe like, body cleansing articles like impregnated wipes/tissues (e.g.baby wipes, wipes for feminine intimate hygiene), and the like, andarticles for animals like litters and the like.

By “bodily fluid and/or bodily exudate” it is meant herein anyexudate/fluid produced by human or animal body occurring naturally oraccidentally like for instance in the case of skin cutting, includingfor instance perspiration, urine, menstrual fluids, faeces, vaginalsecretions and the like.

Cationic Polysaccharides

According to the present invention the articles comprise as an essentialcomponent a cationic polysaccharide or a mixture thereof.

Suitable cationic polysaccharides for use herein are positively chargedpolysaccharides due to the presence of cationic functional groups.Suitable polysaccharides for use herein include natural andsemi-synthetic cationic polysaccharides. Examples of suitable cationicfunctional groups include primary, secondary or tertiary amine groups orquaternary ammonium groups, which should be present in base form.Preferably quaternary ammonium groups are present. The cationicpolysaccharides for use herein might be a fibrous polysaccharide such ascellulose with an excess of quaternary ammonium compound containing atleast one group capable of reacting with polysaccharide hydroxyl groups.Such cationic polysaccharides are described in WO 92/19652 and WO96/17681, herein incorporated by reference. Highly preferred herein areaminopolysaccharides, namely chitin-based materials, chitosan materialsand mixture thereof.

By ‘chitosan material’ it is meant herein chitosans, modified chitosans,crosslinked chitosans and chitosan salts.

Chitosan is a partially or fully deacetylated form of chitin, anaturally occurring polysaccharide. Indeed, chitosan is anaminopolysaccharide usually prepared by deacetylation of chitin(poly-beta (1,4)-N-acetyl-D-glucosamine).

Chitin occurs widely in nature, for example, in the cell walls of fungiand the hard shell of insect and crustaceans. The waste from shrimp-,lobster, and crab seafood industries typically contains about 10 toabout 15 percent chitin and is a readily available source of supply. Inthe natural state, chitin generally occurs only in small flakes or shortfibrous material, such as from the carapace or tendons of crustaceans.There is generally no source, as with cotton in the cellulosics, thatforms useful shaped articles without solution and re-precipitation orre-naturing.

More specifically, chitin is a mucopolysaccharide,poly-N-acetyl-D-glucosamine with the following formula:

wherein x represents the degree of polymerization. Although x cannot bedetermined precisely, x is believed to be commonly in the range of fromabout 30 to about 50,000.

Chitosan is not a single, definite chemical entity but varies incomposition depending on the conditions of manufacture. It may beequally defined as chitin sufficiently deacetylated to form solubleamine salts. Chitosan is the beta-(1-4) polysaccharide of D-glucosamine,and is structurally similar to cellulose, except that the C-2 hydroxylgroup in cellulose is substituted with a primary amine group inchitosan. The large number of free amine groups makes chitosan apolymeric weak base. Solutions of chitosan are generally highly viscous,resembling those of natural gums.

The chitosan used herein is suitably in relatively pure form. Methodsfor the manufacture of pure chitosan are well known. Generally, chitinis milled into a powder and demineralized with an organic acid such asacetic acid. Proteins and lipids are then removed by treatment with abase, such as sodium hydroxide, followed by chitin deacetylation bytreatment with concentrated base, such as 40 percent sodium hydroxide.The chitosan formed is washed with water until the desired pH isreached.

The properties of the aminopolyssaccharides, especially chitosan, relateto their polyelectrolyte and polymeric carbohydrate character. Thus,chitosan is generally insoluble in water, in alkaline solutions at pHlevels above about 6.5, or in organic solvents. It generally dissolvesreadily in dilute solutions of organic acids such as formic, acetic,tartaric, glycolic, lactic and citric acids, and also in dilute mineralacids, except, for example, sulfuric acid. In general, the amount ofacid required to dissolve chitosan is approximately stoichiometric withthe amino groups. Since the pKa for the amino groups present in chitosanmaterial is between 6.0 and 7.0, they can be protonated in very diluteacids or even close to neutral conditions, rendering a cationic natureto this biopolymer. This cationic nature is the basis of many of thebenefits of the chitosan material. More generally, the cationicpolysaccharides, like chitosan materials, can be considered as a linearpolyelectrolyte with a high charge density which can interact withnegatively charged surfaces, like proteins (e.g., by interfering withthe negatively charged wall construction of microorganisms and/orenzymes, thereby acting as an antimicrobial agent and/or by reactingwith the proteins present in bodily fluid, like menses, thereby actingas a gelifying agent for such fluid) or like anionic absorbent gellingmaterials that might be present in the articles herein as an optionalingredient (e.g., in a preferred embodiment of the present invention,thereby further enhancing the odor control properties of the cationicpolysaccharides and providing outstanding absorption properties even inpresence of electrolyte-containing solutions).

Preferred chitosan materials for use herein have an average degree ofdeacetylation (D.A.) of more than 75%, preferably from 80% to about100%, even more preferably from 90% to 100% and most preferably from 95%to about 100%. The degree of deacetylation refers to the percentage ofthe amine groups that are deacetylated. This characteristic is directlyrelated to the hydrogen bonding existing in this biopolymer, affectingits structure, solubility and ultimately its reactivity. The degree ofdeacetylation can be determined by titration, dye adsorption, UV-VIS,IR, and NMR spectroscopy.

The degree of deacetylation will influence the cationic properties ofchitosan materials. By increasing the degree of deacetylation thecationic character of chitosan materials will increase and thus theirantimicrobial properties, absorbing ability and gelifying ability.

Suitable chitosan materials to use herein include both water-soluble andwater insoluble chitosan. As used herein, a material will be consideredto be water-soluble when it substantially dissolves in excess water toform a clear and stable solution, thereby, losing its initiallyparticulate form and becoming essentially molecularly dispersedthroughout the water solution. Particularly suitable chitosan materialsfor use herein are water soluble, i.e., at least 0.5 gram, preferably atleast 1 gram and most preferably at least 2 grams of the chitosanmaterials are soluble in 100 grams of water at 25° C. and oneatmosphere. By “solubility” of a given compound it is to be understoodherein the amount of said compound solubilised in de-ionized water at25° C. and one atmosphere in absence of precipitate.

As a general rule, the water-soluble chitosan materials will be freefrom a substantial degree of crosslinking, as crosslinking tends torender the chitosan materials water insoluble.

Water-soluble chitosan materials as defined herein have the benefit tobe more active in terms of odor control towards most of the malodorouscompounds, present and soluble in the bodily fluid. Indeed suchwater-soluble chitosan materials have the ability to absorb and/orelectrostatically interfere with water-soluble malodorous componentslike short chain acid (e.g., butyric acid) or low molecular weightalcohol (e.g., ethanol).

Chitosan materials (i.e., chitosan and -chitosan salts, modifiedchitosans and cross-linked chitosans) may generally have a wide range ofmolecular weights. Chitosan materials with a wide range of molecularweights are suitable for use in the present invention, typicallychitosan materials for use herein have a molecular weight ranging from 1000 to 10 000 000 grams per gram moles and more preferably from 2 000 to1 000 000. Molecular weight means weight average molecular weight.Methods for determining the weight average molecular weight of chitosanmaterials are known to those skilled in the art. Typical methods includefor example light scattering, intrinsic viscosity and gel permeationchromatography. It is generally most convenient to express the molecularweight of a chitosan material in terms of its viscosity in a 1.0 weightpercent aqueous solution at 25° C. with a Brookfield viscometer. It iscommon to indirectly measure the viscosity of the chitosan material bymeasuring the viscosity of a corresponding chitosan salt, such as byusing a 1.0 weight percent acetic acid aqueous solution. Chitosanmaterials suitable for use in the present invention will suitably have aviscosity in a 1.0 weight percent aqueous solution at 25° C. of fromabout 1 mPa·s (1 centipoise) to about 80,000 mPa·s (80,000 centipoise),more suitably from about 30 mPa·s (30 centipoise) to about 10,000 mPa·s(10,000 centipoise), even more suitably from 50 mPa·s (50 centipoise) toabout 1,000 mPa·s (1,000 centipoise) and most suitably from 100 mPa·s(100 centipoise) to about 500 mPa·s (500 centipoise).

Chitosan materials pH depends on the preparation of the chitosanmaterials. Preferred chitosan materials for use herein have an acidicpH, typically in the range of 4 to 6, more preferably from 4 to 5.5 andeven more preferably from 4.5 to 5.5. Highly preferred pH is around pH5, which corresponds to the skin pH. By pH of chitosan material it ismeant herein the pH of a 1% chitosan solution (1 gram of chitosanmaterial dissolved in 100 grams of distilled water) measured bypH-meter.

The cationic properties of the chitosan materials and thus theirantimicrobial, absorbing ability and gelifying ability increase withtheir acidic character. However too high acidity is detrimental to skinsafety. Thus it is highly preferred herein to use chitosan materialswith a pH in the range of 4.5 to 5.5, thereby delivering the bestcompromise between odor control and fluid handling properties on oneside and skin compatibility on the other side.

Particularly suitable aminopolysaccharides for use herein includeaminopolysaccharide salts, especially chitosan salts. A variety of acidscan be used for forming aminopolysaccharide salts like chitosan salts.Suitable acids for use are soluble in water or partially soluble inwater, are sufficiently acidic to form the ammonium salt of theaminopolysaccharide and yet not sufficiently acidic to cause hydrolysisof the aminopolysaccharide, and are present in amount sufficient toprotonate the reactive sites of the deacetylated aminopolysaccharide.

Preferred acids can be represented by the formula:R—(COOH)_(n)

wherein n has a value of 1 or 2 or 3 and R represents a mono- ordivalent organic radical composed of carbon, hydrogen and optionally atleast one of oxygen, nitrogen and sulfur or R is simply a hydroxylgroup. Preferred acids are the mono- and dicarboxylic acids composed ofcarbon, hydrogen, oxygen and nitrogen (also called herein after aminoacids). Such acids are highly desired herein as they are biologicallyacceptable for use against or in proximity to the human body.Illustrative acids, in addition to those previously mentioned include,among others, citric acid, formic acid, acetic acid, N-acetylglycine,acetylsalicylic acid, fumaric acid, glycolic acid, iminodiacetic acid,itaconic acid, lactic acid, maleic acid, malic acid, nicotinic acid,2-pyrrolidone-5-carboylic acid, salicylic acid, succinamic acid,succinic acid, ascorbic acid, aspartic acid, glutamic acid, glutaricacid, malonic acid, pyruvic acid, sulfonyldiacetic acid, benzoic acid,epoxysuccinic acid, adipic acid, thiodiacetic acid and thioglycolicacid. Any aminopolysaccharide salts, especially chitosan salts formedfrom the reaction of the aminopolysaccharide with any of these acids aresuitable for use herein.

Examples of chitosan salts formed with an inorganic acid include, butare not limited to, chitosan hydrochloride, chitosan hydrobromide,chitosan phosphate, chitosan sulphonate, chitosan chlorosulphonate,chitosan chloroacetate and mixtures thereof. Examples of chitosan saltsformed with an organic acid include, but are not limited to, chitosanformate, chitosan acetate, chitosan lactate, chitosan glycolate,chitosan malonate, chitosan epoxysuccinate, chitosan benzoate, chitosanadipate, chitosan citrate, chitosan salicylate, chitosan propionate,chitosan nitrilotriacetate, chitosan itaconate, chitosan hydroxyacetate,chitosan butyrate, chitosan isobutyrate, chitosan acrylate, and mixturesthereof. It is also suitable to form a chitosan salt using a mixture ofacids including, for example, both inorganic and organic acids.

Preferred aminopolysaccharide salts, and especially chitosan salts foruse herein are those formed by the reaction of aminopolysaccharides withan amino acid. Amino acids are molecules containing both an acidic andamino functional group. The use of amino acids is highly preferred asthose aminopolysaccharide amino salts have higher skin compatibility.Indeed most of the amino acids are naturally present on the skin andthus are non-irritating. Chitosan salts of pyrrolidone carboxylic acidare effective moisturizing agents and are non-irritating to skin. Suchchitosan materials are suitable in case of accidental low rewettingoccurrence and/or misuse of the articles.

Amino acids for use herein include both linear and/or cyclo amino acids.Examples of amino acids for use herein include, but are not limited to,alanine, valine, leucine, isoleucine, prolinephenylalanine, triptofane,metionine, glycine, serine, cysteine, tyrosine, asparagine, glutamine,aspartic acid, glutamic acid, lysine, arginine, istydine, hydroxyprolineand the like. A particularly suitable example of cyclo amino acid ispyrrolidone carboxylic acid, which is a carboxylic acid ofpyrrolidin-2-one as per following formula:

Highly preferred chitosan salts are chitosan pyroglutamate salt, whichis a mixture of chitosan (a macromolecule) and pyroglutamic acid(independent monomers), chitosonium pyrrolidone carboxylate, which isthe chitosan salt of 2-pyrrolidone-5-carboxylic acid.

Reference is made to WO 98/07618, which describes in details processesfor the preparation of such aminopolysaccharide salts.

Other aminopolysaccharide materials suitable for use herein includecross-linked aminopolysaccharides and modified aminopolysaccharides,especially cross-linked chitosans and modified chitosans.

Suitable crosslinking agents for use herein are organic compounds havingat least two functional groups or functionalities capable of reactingwith active groups located on the aminopolysaccharide, typicallychitosan materials. Examples of such active groups include, but are notlimited to, carboxylic acid (—COOH), or hydroxyl (—OH) groups. Examplesof such suitable crosslinking agents include, but are not limited to,diamines, polyamines, diols, polyols, dicarboxylic acids, polycarboxylicacids, aminocarboxylic acids, aminopolycarboxylic acids polyoxides andthe like. One way to introduce a crosslinking agent with the chitosansolution is to mix the crosslinking agent with chitosan duringpreparation of the solution. Another suitable crosslinking agentcomprises a metal ion with more than two positive charges, such as Ca²⁺,Al³⁺, Fe³⁺, Ce³⁺, Ce⁴⁺, Ti⁴⁺, Zr⁴⁺, and Cr³⁺. Since the cations onchitosan possess antimicrobial properties, it is preferred herein to notuse a crosslinking agent reacting to the cations, unless no alternativecrosslinking agent is available.

In the embodiment herein where crosslinking agents are used, a suitableamount of crosslinking agent is from 0.001 to 30 weight percent based onthe total dry weight of chitosan used to prepare thecrosslinked-chitosan, more specifically from 0.02 to 20 weight percent,more specifically from 0.05 to 10 weight percent and most preferablyfrom 0.1 to 5 weight percent.

Modified chitosans or chitins for use herein are any chitosan or chitinwhere the glucan chains carry pendant groups. Examples of such modifiedchitosans include carboxymethyl chitosan, methyl pyrrolidinone chitosan,glycol chitosan and the like. Methyl pyrrolidone chitosan is forinstance described in U.S. Pat. No. 5,378,472, incorporated herein byreference. Water-soluble glycol chitosan and carboxymethyl chitosan arefor instance described in WO 87/07618, incorporated herein by reference

Particularly suitable modified chitosans for use herein includewater-soluble covalently bonded chitosan derivatives or ionically bondedchitosan derivatives obtained by contacting salt of chitosan withelectrophilic organic reagents. Such water-soluble chitosan derivativesare described in EP-A737 692, which is herein incorporated by reference.

Suitable electrophilic organic reagents suitable for use for thepreparation of chitosan derivatives contain from 2 to 18 carbon atoms ormore per molecule and typically from 2 to 10 carbon atoms per molecule.In addition the electrophilic organic reagents contain groups, which arereactive, i.e. capable of forming a covalent bond with a nucleophile.Typical electrophilic organic reagents include, for example, ethyleneoxide, propylene oxide, butylene oxide, glycidol,3-chloro-1,2-propanediol, methyl chloride, ethyl chloride, isatoicanhydride, succinic anhydride, octenylsuccinic anhydride, aceticanhydride, gamma-butyrolactone, b-propiolactone, 1,3-propanesultone,acrylamide, glycidyltrimethyl ammonium chloride, glycidyldimethylalkylammonium chloride such as lauryl, sodium chlorosulfonate, dimethylsulfate, sodium chloroethanesulfonate, monochloroacetic acid, alkylphenyl glycidyl ethers, glycidyl trimethoxysilanes, 1,2-epoxy dodecane.One preferred class of electrophilic organic reagent includes thoseelectrophilic organic reagents, which contain an epoxide group, at leastone acid group, preferably a diacid group and have from 3 to 18,preferably from 3 to 6 carbon atoms per molecule. Other preferredelectrophilic organic reagents include cis-electrophilic organicreagents and trans-electrophilic organic reagent, with cis-electrophilicorganic reagents being especially preferred. The electrophilic organicreagent may react with either the free amine or the underivatizedhydroxyl groups of the chitosan. It is known that the aminefunctionality of the chitosan is generally regarded as a strongernucleophilic site than the hydroxyl groups. Consequently weakerelectrophiles will tend to react more readily with the amine groups thanwith the hydroxyl groups of the chitosan.

Preferably an effective amount of electrophilic organic reagent issubstituted onto the chitosan to achieve the desired properties of thechitosan derivative, namely its water-soluble properties. Typically thechitosan derivatives suitable for use herein (modified chitosan) have aMS of from 0.03 to 10 moles of the electrophilic organic reagent permole of glucosamine monomer unit. The term molar substitution (MS),means the moles of electrophilic organic reagent substituted on thechitosan per mole of glucosamine monomer unit.

In addition further modified chitosan can be prepared which containother substituent groups, such as hydroxalkyl ether group (e.g.,hydroxyethyl or hydroxypropyl ether groups), carboxyalkyl ether groups(e.g., carboxymethyl group), amide groups (e.g., succinyl groups), estergroups (e.g., acetate groups) or amino groups (e.g.,3-(trimethylammonium chloride)-2-hydroxylpropyl or3-(dimethyloctadecylammonium chloride)-2-hydroxpropyl ether groups) inaddition to the electrophilic organic reagent groups. These othersubstituent groups may be introduced prior to or subsequent to thereaction with the electrophilic organic reagent, or introducedsimultaneously by reaction of the chitosan salt with the electrophilicorganic reagent and the other derivatizing reagent.

Typically such covalently bonded chitosan derivative might be obtainableby a process which includes the step of (a) dispersing a salt ofchitosan (e.g., any one of those described herein before) in aneffective amount of an aqueous caustic medium to form a neutralizedchitosan containing free amine groups, (b) introducing an electrophilicorganic reagent in the slurry and (c) maintaining the slurry at atemperature and time effective to promote the substitution of theelectrophilic organic reagent onto the chitosan to form a covalentlybonded chitosan derivative and the dissolution of the covalently bondedchitosan into the aqueous medium. The chitosan derivatives can beprepared in either salt form, i.e., ionically bonded, or in thecovalently bonded form. Processes for the preparation of such chitosanderivatives are described in depth in EP-A-737 692, incorporated hereinby reference.

Suitable chitosans are commercially available from numerous vendors.Exemplary of a commercially available chitosan materials are thoseavailable from for example the Vanson Company. The preferred chitosansalt for use herein is chitosan pyrrolidone carboxylate (also calledchitosonium pyrrolidone carboxylate), which has a degree ofdeacetylation more than 85%, a water solubility of 1% (1 gram is solublein 100 grams of distilled water at 25° C. and one atmosphere), a pH of4.5 and a viscosity between 100-300 cps. Chitosan pyrrolidonecarboxylate is commercially available under the name Kytamer® PC fromAmerchol Corporation.

Typically, the articles like disposable absorbent articles comprise thecationic polysaccharide or a mixture thereof at a level of from 0.5 gm⁻²to 500 gm⁻², preferably from 1 to 200 gm⁻², more preferably from 3 gm⁻²to 100 gm⁻² and most preferably from 4 gm⁻² to 50 gm⁻²

The Odor Controlling Agents

The articles according to the present invention further comprise on topof the cationic polysaccharide or mixture thereof described hereinbefore, at least one additional odor-controlling agent or a mixturethereof.

Typically, the articles like disposable absorbent articles hereincomprise from 1 to 600 gm⁻², more preferably from 5 to 400 gm⁻², mostpreferably from 10 to 200 gm⁻², of the odor controlling agent or amixture thereof.

Suitable odor controlling agents for use herein include odor absorbentagents known to those skilled in the art, namely activated carbons,clays, zeolites, kieselguhr, diatomaceous earth, starches, cyclodextrin,ion exchange resins and the like. Preferred herein are zeolites and/orcyclodextrin. Other suitable odor controlling agents for use hereininclude chelating agents or a mixture thereof. The articles herein maycontain mixtures of odor absorbent agents with chelating agents.

The present invention is based on the finding that the cationicpolysaccharides, especially chitosan materials, together with an odorcontrolling agent, preferably an odor absorbent agent (preferablyzeolite and/or cyclodextrin) and/or a chelating agent (preferablyethylene diamine tetra acetates) deliver a synergistic odor controlbenefit towards malodors associated with bodily fluids, especiallymenses.

It is speculated that the cationic polysaccharides herein prevent theformation of malodorous compounds, typically by reducing or eveninhibiting the microbial and enzymatic development in bodily fluid,thereby reducing the total amount of malodorous compounds associatedwith bodily fluid. This results in more effective use of odor absorbentagents over prolonged period of time before the saturation of the activecenter of absorption of such agents. Advantageously these odor absorbentagents, like zeolite or cyclodextrine or derivatives thereof, controlodor associated with bodily fluids/exudates not only by absorbingmalodorous components present in the bodily fluids coming into contacttherewith, typically in the absorbent article, but also by absorbing thevolatile malodorous components present in the headspace of the absorbentarticle which would otherwise not have been controlled in presence ofthe cationic polysaccharides used alone as the sole odor controllingagent in the absorbent article.

In a preferred embodiment herein the cationic polysaccharide and theodor absorbent agent are present in weight ratio from the cationicpolysaccharide to the odor absorbent agent of from 1:10 to 10:1,preferably from 1:5 to 5:1 and more preferably at a ratio around 1:1.Indeed it is within these ratios ranges that optimum odor controlproperties are obtained versus bodily fluids.

Zeolite

A particularly suitable odor absorbent agent herein is zeolite. The useand manufacture of zeolite material is well know in the literature andis described in the following reference texts: ZEOLITE SYNTHESIS, ACSSymposium Series 398, Eds. M. L. Occelli and H. E Robson (1989) pages2-7; ZEOLITE MOLECULAR SIEVES, Structure, Chemistry and Use, by D. W.Breck, John Wiley and Sons (1974) pages 245-250, 313-314 and 348-352;MODERN APPLICATIONS OF MOLECULAR SIEVE ZEOLITES, Ph.D. Dissertation ofS. M. Kuznicki, U. of Utah (1980), available from University ofMicrofilms International, Ann Arbor, Mich., pages 2-8.

Zeolites are crystalline aluminosilicates of group IA and group IIAelements such as Na, K, Mg, and Ca are chemically represented by theempirical formula:

 M_(2/n)O.Al₂O₃.ySiO₂.wH₂O

where y is 2 or greater, n is the cation valence, and w is the watercontent in the voids of the zeolite.

Structurally, zeolites are complex, crystalline inorganic polymers basedon an infinitely extending framework of AlO₄ and SiO₄ tetrahedra linkedto each other by sharing of oxygen ions. This framework structurecontains channels or interconnected voids that are occupied by thecations and water molecules.

The structural formula of a zeolite is based on the crystal unit cell,the smallest unit of structure, represented byM_(x/n)[(AlO₂)_(x)(SiO₂)y].wH₂O

where n is the valence of cation M, w is the number of water moleculesper unit cell, x and y are the total number of tetrahedra per unit cell,y/x usually having values of 1-5.

Zeolites may be naturally derived or synthetically manufactured. Thesynthetic zeolites being preferred for use herein. Suitable zeolites foruse herein include zeolite A, zeolite P, zeolite Y, zeolite X, zeoliteDAY, zeolite ZSM-5, or mixtures thereof. Most preferred is zeolite A.

According to the present invention the zeolite is preferablyhydrophobic. This is typically achieved by increasing the molar ratio ofthe SiO₂ to AlO₂ content such that the ratio of x to y is at least 1,preferably from 1 to 500, most preferably from 1 to 6.

According to the present invention the articles typically comprise from0 to 300 gm⁻², more preferably from 40 to 250 gm⁻² most preferably from60 to 200 gm⁻², of zeolite based on 100% purity or a mixture thereof.

Cyclodextrin and Derivatives Thereof

A particularly suitable odor absorbent agent for use herein iscyclodextrin or a derivative thereof or a mixture thereof. Thesematerials are preferred herein due to their dual function ofsolubilising cationic polysaccharides, typically those that are partlywater soluble or non water-soluble and of their own ability to absorbodor.

Cyclodextrin or a derivative thereof may thus act as a carrier for thecationic polysaccharides, typically chitosan materials, and thuscontribute to bring chitosan materials, especially those being partlywater soluble or non soluble (i.e., typically having a solubility inwater of less than 0.5 gram per 100 grams of distilled water at 25° C.and one atmosphere), into closer contact with the liquid bodily fluidand thus the water soluble malodorous components resulting from thedegradation of lipids, proteins and/or sugars like amine, butyric acidand the like. It is speculated that cyclodextrin or derivatives thereofhelp to further solubilise the cationic polysaccharides and this resultsin significantly improved overall odor control (synergistic effect).

The unique shape and physical-chemical property of the cavity enable thecyclodextrin molecules to absorb (form inclusion complexes with) organicmolecules or parts of organic molecules, which can fit into the cavity.

As used herein, the term “cyclodextrin” includes any of the knowncyclodextrins such as unsubstituted cyclodextrins containing from six totwelve glucose units, especially, alpha-cyclodextrin, beta-cyclodextrin,gamma-cyclodextrin and/or their derivatives and/or mixtures thereof. Thealpha-cyclodextrin consists of six glucose units, the beta-cyclodextrinconsists of seven glucose units, and the gamma-cyclodextrin consists ofeight glucose units arranged in a donut-shaped ring. The specificcoupling and conformation of the glucose units give the cyclodextrins arigid, conical molecular structure with a hollow interior of a specificvolume. The “lining” of the internal cavity is formed by hydrogen atomsand glycosidic bridging oxygen atoms; therefore this surface is fairlyhydrophobic. Non-derivatised (normal) beta-cyclodextrin can be usedherein.

Particularly preferred cyclodextrins useful in the present invention arehighly water-soluble such as, alpha-cyclodextrin and derivativesthereof, gamma-cyclodextrin and derivatives thereof, derivatisedbeta-cyclodextrins, and/or mixtures thereof.

The derivatives of cyclodextrin consist mainly of molecules wherein someof the OH groups are converted to OR groups. Cyclodextrin derivativesinclude, e.g., those with short chain alkyl groups such as methylatedcyclodextrins, and ethylated cyclodextrins, wherein R is a methyl or anethyl group; those with hydroxyalkyl substituted groups, such ashydroxypropyl cyclodextrins and/or hydroxyethyl cyclodextrins, wherein Ris a —CH₂—CH(OH)—CH₃ or a —CH₂CH₂—OH group; branched cyclodextrins suchas maltose-bonded cyclodextrins; cationic cyclodextrins such as thosecontaining 2-hydroxy-3(dimethylamino)propyl ether, wherein R isCH₂—CH(OH)—CH₂—N(CH₃)₂ which is cationic at low pH; quatemary ammonium,e.g., 2-hydroxy-3-(trimethylammonio)propyl ether chloride groups,wherein R is CH₂—CH(OH)—CH₂—N⁺(CH₃)₃Cl⁻; anionic cyclodextrins such ascarboxymethyl cyclodextrins, cyclodextrin sulfates, and cyclodextrinsuccinylates; amphoteric cyclodextrins such as carboxymethyl/quatemaryammonium cyclodextrins; cyclodextrins wherein at least one glucopyranoseunit has a 3-6-anhydro-cyclomalto structure, e.g., themono-3-6-anhydrocyclodextrins, as disclosed in “Optimal Performanceswith Minimal Chemical Modification of Cyclodextrins”, F. Diedaini-Pilardand B. Perly, The 7th International Cyclodextrin Symposium Abstracts,April 1994, p. 49, herein incorporated by reference; and mixturesthereof. Other cyclodextrin derivatives are disclosed in U.S. Pat. No.3,426,011, Parmerter et al., issued Feb. 4, 1969; U.S. Pat. Nos.3,453,257; 3,453,258; 3,453,259; and 3,453,260, all in the names ofParmerter et al., and all issued Jul. 1, 1969; U.S Pat. No. 3,459,731,Gramera et al., issued Aug. 5, 1969; U.S. Pat. No. 3,553,191, Parmerteret al., issued Jan. 5, 1971; U.S. Pat. No. 3,565,887, Parmerter et al.,issued Feb. 23, 1971; U.S. Pat. No. 4,535,152, Szejtli et al., issuedAug. 13, 1985; U.S. Pat. No. 4,616,008, Hirai et al., issued Oct. 7,1986; U.S. Pat. No. 4,678,598, Ogino et al., issued Jul. 7, 1987; U.S.Pat. No. 4,638,058, Brandt et al., issued Jan. 20, 1987; and U.S. Pat.No. 4,746,734, Tsuchiyama et al., issued May 24, 1988; all of saidpatents being incorporated herein by reference.

Highly water-soluble cyclodextrins are those having water solubility ofat least about 10 g in 100 ml of water at room temperature, preferablyat least about 20 g in 100 ml of water, more preferably at least about25 g in 100 ml of water at room temperature. These are easy to use, butare typically more expensive than the non-derivatised beta-cyclodextrin.Examples of preferred water-soluble cyclodextrin derivatives suitablefor use herein are hydroxypropyl alpha-cyclodextrin, methylatedalpha-cyclodextrin, methylated beta-cyclodextrin, hydroxyethylbeta-cyclodextrin, and hydroxypropyl beta-cyclodextrin. Hydroxyalkylcyclodextrin derivatives preferably have a degree of substitution offrom about 1 to about 14, more preferably from about 1.5 to about 7,wherein the total number of OR groups per cyclodextrin is defined as thedegree of substitution. Methylated cyclodextrin derivatives typicallyhave a degree of substitution of from about 1 to about 18, preferablyfrom about 3 to about 16. A known methylated beta-cyclodextrin isheptakis-2,6-di-O-methyl-β-cyclodextrin, commonly known as DIMEB, inwhich each glucose unit has about 2 methyl groups with a degree ofsubstitution of about 14. A preferred, more commercially availablemethylated beta-cyclodextrin is a randomly methylated beta-cyclodextrinhaving a degree of substitution of about 12.6. The preferredcyclodextrins are available, e.g., from Cerestar USA, Inc. and WackerChemicals (USA), Inc.

It can be desirable to use a mixture of cyclodextrins. Such mixtures cancomplex with a wider range of odor molecules having a wider range ofmolecular sizes. Preferably at least a portion of such a mixture ofcyclodextrins is alpha-cyclodextrin or its derivatives,gamma-cyclodextrin or its derivatives thereof, and/or beta-cyclodextrinor its derivatives.

According to the present invention the articles typically comprise from0 to 300 gm⁻², more preferably from 5 to 250 gm⁻² most preferably from 7to 200 gm⁻², of cyclodextrin or derivative thereof or mixture thereof.

Chelating Agents

Suitable chelating agents for use herein are those known to thoseskilled in the art. Suitable chelating agents include for examplephosphonate chelating agents, polyfunctionally-substituted aromaticchelating agents, amino carboxylate chelating agents, other chelatingagents like ethylene diamine N,N′-disuccinic acid, aspartic acid,glutamic acid, malonic acid, glycine and mixtures thereof.

Suitable phosphonate chelating agents to be used herein may includeethydronic acid, alkali metal ethane 1-hydroxy diphosphonates as well asamino phosphonate compounds, including amino alkylene poly (alkylenephosphonate), alkali metal ethane 1-hydroxy diphosphonates, nitrilotrimethylene phosphonates, ethylene diamine tetra methylenephosphonates, aminotri(methylene phosphonates) (ATMP) and diethylenetriamine penta methylene phosphonates. The phosphonate compounds may bepresent either in their acid form or as salts of different cations onsome or all of their acid functionalities. Typically, these aminophosphonates do not contain alkyl or alkenyl groups with more than 6carbon atoms. Preferred phosphonate chelating agents to be used hereinare diethylene triamine penta methylene phosphonates (DETPMP). Suchphosphonate chelating agents are commercially available from Monsantounder the trade name DEQUEST®.

Polyfunctionally-substituted aromatic chelating agents may also beuseful in the compositions herein. See U.S. Pat. No. 3,812,044, issuedMay 21, 1974, to Connor et al. Preferred compounds of this type in acidform are dihydroxydisulfobenzenes such as1,2-dihydroxy-3,5-disulfobenzene.

A preferred biodegradable chelating agent for use herein is ethylenediamine N,N′-disuccinic acid, or alkali metal, or alkaline earth,ammonium or substitutes ammonium salts thereof or mixtures thereof.Ethylenediamine N,N′-disuccinic acids, especially the (S,S) isomer havebeen extensively described in U.S. Pat. No. 4,704,233, Nov. 3, 1987. toHartman and Perkins. Ethylenediamine N,N′-disuccinic acids is, forinstance, commercially available under the trade name ssEDDS® fromPalmer Research Laboratories.

Suitable amino carboxylate chelating agents to be used herein includeethylene diamine tetra acetates (EDTA), diethylene triaminepentaacetates, diethylene triamine pentaacetate (DTPA),N-hydroxyethylethylenediamine triacetates, nitrilotri-acetates,ethylenediamine tetrapropionates, triethylenetetraaminehexa-acetates,diethylenetriamine pentaacetates, ethanol-diglycines, propylene diaminetetracetic acid (PDTA) and methyl glycine di-acetic acid (MGDA), both intheir acid form, or in their alkali metal, ammonium, and substitutedammonium salt forms. Particularly suitable amino carboxylates to be usedherein are ethylene diamine tetra acetates (EDTA), diethylene triaminepenta acetic acid (DTPA) or mixture thereof.

The more preferred chelating agents for use herein are selected fromethylenediamine tetracetate, -triacetate, -diacetate, and -monoacetate,ethylenediamine N,N,-disuccinic acid (sodium salt), ethylenediaminepenta (methylene phosphonic acid) (sodium salt), ethylenediamine tetra(methylene phosphonic acid) or mixtures thereof. Most preferably thechelating agent is ethylene diamine tetracetate.

According to the present invention the articles typically comprise from0 to 300 gm⁻², more preferably from 5 to 250 gm⁻² most preferably from 7to 200 gm⁻², of chelating agent or mixture thereof.

It is speculated that the chelating agents herein participate to theantimicrobial activities of the cationic polysaccharides herein. Indeedthey chelate positively charged nutriments for microorganisms likegrowth factors (e.g., calcium, magnesium and/or potassium) that arevital for any microbial development, thereby reducing such development.They thus supplement the antimicrobial direct activity of the cationicpolysaccharides herein, especially chitosan materials. This is even morethe case in the preferred embodiments of the present invention, wherechitosan materials with high degree of deacetylation are used (more than75%) as defined herein, and where as a consequence such chitosanmaterials are not able to act as chelating agents towards positivelycharged nutriments.

In a preferred embodiment herein the cationic polysaccharide and thechelating agent are present in weight ratio from the cationicpolysaccharide to the chelating agent of from 1:10 to 10:1, preferablyfrom 1:5 to 5:1 and more preferably from 1:3 to 3:1. Indeed it is withinthese ratios ranges that optimum odor control properties are obtainedversus bodily fluids.

Optional Agents

The articles according to the present invention may further compriseother conventional agents like absorbent gelling materials.

Absorbent Gelling Materials

As is well known from recent commercial practice, absorbent gellingmaterials (sometimes referred to as “super-sorbers”) are becomingbroadly used in absorbent articles. AGMs are materials, which have thetwofold property of absorbing and retaining fluids and odors, and thusfurther contribute to the benefit of the present invention.

Particularly preferred absorbent gelling materials for use herein areanionic absorbent gelling materials, i.e., absorbent gelling materialsthat are predominantly negatively charged. These absorbent gellingmaterials can be any material having superabsorbent properties in whichthe functional groups are anionic, namely sulphonic groups, sulphategroups, phosphate groups or carboxyl groups. Preferably the functionalgroups are carboxyl groups. Particularly preferred anionic absorbentgelling materials for use herein are synthetic anionic absorbent gellingmaterials. Synthetic anionic absorbent gelling materials are preferredherein as they deliver higher odor and fluid absorption performance,this even under pressure, as compared to the absorption performanceassociated with natural anionic absorbent gelling materials like anionicpolysaccharides when used in the same absorbent article.

Generally the functional groups are attached to a slightly cross-linkedacrylic base polymer. For example the base polymer may be apolyacrylamide, polyvinyl alcohol, ethylene maleic anhydride copolymer,polyvinylether, polyvinyl sulphonic acid, polyacrylic acid,polyvinylpyrrolidone and polyvinylmorpholine. Copolymers of thesemonomers can also be used. Particular base polymers include cross-linkedpolyacrylates, hydrolyzed acrylonitrile grafted starch, starchpolyacrylates and isobutylene maleic anhydride copolymers.

Such materials form hydrogels on contact with water (e.g., with urine,blood, and the like). One highly preferred type of hydrogel-forming,absorbent gelling material is based on polyacids, especially polyacrylicacid. Hydrogel-forming polymeric materials of this type are those,which, upon contact with fluids (i.e., liquids) such as water or bodyfluids, imbibe such fluids and thereby form hydrogels. These preferredabsorbent gelling materials will generally comprise substantiallywater-insoluble, slightly cross-linked, partially neutralized,hydrogel-forming polymer materials prepared from polymerisable,unsaturated, acid-containing monomers. In such materials, the polymericcomponent formed from unsaturated, acid-containing monomers may comprisethe entire gelling agent or may be grafted onto other types of polymermoieties such as starch or cellulose. Acrylic acid grafted starchmaterials are of this latter type. Thus, the preferred absorbent gellingmaterials include hydrolyzed acrylonitrile grafted starch, acrylic acidgrafted starch, polyacrylates, maleic anhydride-based copolymers andcombinations thereof. Especially preferred absorbent gelling materialsare the polyacrylates and acrylic acid grafted starch.

Whatever the nature of the polymer components of the preferred absorbentgelling materials, such materials will in general be slightlycross-linked. Crosslinking serves to render these preferredhydrogel-forming absorbent materials substantially water-insoluble, andcross-linking also in part determines the gel volume and extractablepolymer characteristics of the hydrogels formed there from. Suitablecross-linking agents are well known in the art and include, for example,(1) compounds having at least two polymerisable double bonds; (2)compounds having at least one polymerisable double bond and at least onefunctional group reactive with the acid-containing monomer material; (3)compounds having at least two functional groups reactive with theacid-containing monomer materials; and (4) polyvalent metal compoundswhich can from ionic cross-linkages. Cross-linking agents of theforegoing types are described in greater detail in Masuda et al; U.S.Pat. No. 4,076,663; Issued Feb. 28, 1978. Preferred cross-linking agentsare the di- or polyesters of unsaturated mono-or polycarboxylic acidswith polyols, the bisacrylamides and the di-or triallyl amines.Especially preferred cross-linking agents areN,N′-methylenebisacrylamide, trimethylol propane triacrylate andtriallyl amine. The cross-linking agent will generally comprise fromabout 0.001 mole percent to 5 mole percent of the preferred materials.More preferably, the cross-linking agent will comprise from about 0.01mole percent to 3 mole percent of the gelling materials used herein.

The preferred absorbent gelling materials used herein are those whichhave a relatively high capacity for imbibing fluids encountered in theabsorbent articles; this capacity can be quantified by referencing the“gel volume” of said absorbent gelling materials. Gel volume can bedefined in terms of the amount of synthetic urine absorbed by any givenabsorbent gelling agent buffer and is specified as grams of syntheticurine per gram of gelling agent.

Gel volume in synthetic urine (see Brandt, et al, below) can bedetermined by forming a suspension of about 0.1-0.2 parts of driedabsorbent gelling material to be tested with about 20 parts of syntheticurine. This suspension is maintained at ambient temperature under gentlestirring for about 1 hour so that swelling equilibrium is attained. Thegel volume (grams of synthetic urine per gram of absorbent gellingmaterial) is then calculated from the weight fraction of the gellingagent in the suspension and the ratio of the liquid volume excluded fromthe formed hydrogel to the total volume of the suspension. The preferredabsorbent gelling materials useful in this invention will have a gelvolume of from about 20 to 70 grams, more preferably from about 30 to 60grams, of synthetic urine per gram of absorbent gelling material.

Another feature of the most highly preferred absorbent gelling materialsrelates to the level of extractable polymer material present in saidmaterials. Extractable polymer levels can be determined by contacting asample of preferred absorbent gelling material with a synthetic urinesolution for the substantial period of time (e.g., at least 16 hours)which is needed to reach extraction equilibrium, by then filtering theformed hydrogel from the supernatant liquid, and finally by thendetermining the polymer content of the filtrate. The particularprocedure used to determine extractable polymer content of the preferredabsorbent gelling agent buffers herein is set forth in Brandt, Goldmanand Inglin; U.S. Pat. No. 4,654,039; Issues Mar. 31, 1987, Reissue32,649, The absorbent gelling materials which are especially useful inthe absorbent articles herein are those which have an equilibriumextractable content in synthetic urine of no more than about 17%,preferably no more than about 10% by weight of the absorbent gellingmaterial.

The preferred, slightly cross-linked, hydrogel-forming absorbent gellingmaterials will generally be employed in their partially neutralizedform. For purposes described herein, such materials are consideredpartially neutralized when at least 25 mole percent, and preferably atleast 50 mole percent of monomers used to form the polymer are acidgroup-containing monomers, which have been neutralized with asalt-forming cation. Suitable salt-forming cations include alkali metal,ammonium, substituted ammonium and amines. This percentage of the totalmonomers utilized, which are neutralized acid group-containing monomers,is referred to as the “degree of neutralization”. Typically, commercialabsorbent gelling materials have a degree of neutralization somewhatfrom 25% to 90%.

The absorbent gelling materials herein before described are typicallyused in the form of discrete particles. Such absorbent gelling materialscan be of any desired shape, e.g., spherical or semi-spherical, cubic,rod-like polyhedral, etc. Shapes having a large greatestdimension/smallest dimension ratio, like needles and flakes, are alsocontemplated for use herein. Agglomerates of absorbent gelling materialparticles may also be used.

The size of the absorbent gelling material particles may vary over awide range. For reason of industrial hygiene, average particle sizessmaller than about 30 microns are less desirable. Particles having asmallest dimension larger than about 2 mm may also cause a feeling ofgrittiness in the absorbent article, which is undesirable from aconsumer aesthetics standpoint. Furthermore, rate of fluid absorptioncan be affected by particle size. Larger particles have very muchreduced rates of absorption. Preferred for use herein are absorbentgelling material s particles substantially all of which have a particlesize of from about 30 microns to about 2 mm. “Particle Size” as usedherein means the weighted average of the smallest dimension of theindividual particles.

The amount of absorbent gelling material particles used in the articleaccording to the present invention, especially disposable absorbentarticles, will typically range from 5 gm⁻² to 250 gm⁻², preferably from7 gm⁻² to 150 gm⁻², more preferably from 10 gm⁻² to 100 gm⁻².

Anionic absorbent gelling materials are suitably used on top of thecationic polysaccharides and odor controlling agents herein as theyfurther contribute to enhance the benefices of the present invention.Indeed the anionic absorbent gelling materials enhance the cationicproperties of the cationic polysaccharides, thus their odor controlproperties. Without to be bound by any theory, it is believed that thenegatively charged anionic groups of the anionic absorbent gellingmaterials protonate the cationic polysaccharides, thereby enhancing thecationic properties of for example chitosan materials.

Advantageously the addition of anionic absorbent gelling materials,namely synthetic anionic absorbent gelling materials as described herein(typically having a degree of neutralization of from 25% to 90%) on topof cationic polysaccharides, especially chitosan materials, in anabsorbent article results in outstanding fluid absorption capacity notonly towards water but especially towards electrolytes-containingsolutions like menses.

Furthermore the use of anionic absorbent gelling materials, namelysynthetic anionic absorbent gelling materials as described herein(typically having a degree of neutralization of from 25% to 90%) on topof cationic polysaccharides, especially chitosan materials, in anabsorbent article, exhibit high gel strength during fluid absorption.Indeed this combination results in improved absorption capacity underload conditions, in decreased rewetting and wetting through and henceimproved comfort.

Advantageously the presence of anionic synthetic absorbent gellingagents on top of the odor control system of the present inventionresults in optimum fluid absorption and optimum odor control of malodorstypically associated with bodily fluids.

The Disposable Absorbent Article

The odor control system (i.e., at least a cationic polysaccharide and anodor controlling agent) as well as the optional absorbent gellingmaterial may be incorporated into the absorbent article by any of themethods disclosed in the art, for example layered on the core of theabsorbent article or mixed within the fibers of the absorbent core.

The cationic polysaccharide and the odor-controlling agent arepreferably incorporated between two layers of cellulose tissue.Optionally the system may be bonded between two cellulose tissue layerswith, for example, a hot melt adhesive or any suitable bonding system,as described in WO 94/01069.

In one embodiment of the present invention the cationic polysaccharideand the odor controlling agent are incorporated in a layered structurein accordance with the disclosure of WO 94/01069 or Italian patentapplication number TO 93A 001028. TO 93A 001028 describes a layeredstructure substantially as described in WO 94/01069 with the exceptionthat TO 93A 001028 comprises a much higher quantity of absorbent gellingmaterial in the intermediate layer which is between the fibrous layers(120 gm⁻²) that would be incorporated as an optional component in thepresent invention. The intermediate layer comprises in particular apolyethylene powder as thermoplastic material, which is mixed with theodor controlling agent and cationic polysaccharide. The mixture is thenheated such that the polyethylene melts and glues the laminate layerstogether. Adhesive lines are preferably also placed on the edges of thelaminate to ensure that the edges of the laminate stick and any loosecationic polysaccharide powder and odor controlling agent powder presentdo not fall out of the laminate.

Alternatively, the polyethylene powder may be replaced by a conventionalglue for instance those commercially available from ATO Findley underthe name H20-31® to glue the laminate layers and/or components together.Advantageously this method step allows to avoid the heating stepnecessary when using polyethylene powder.

The cationic polysaccharide and the odor controlling agent may bedistributed homogeneously or non homogeneously over the entire absorbentarticle or in at least one layer of the topsheet, or at least one layerof the backsheet or in at least one layer of the core or any mixturethereof. The cationic polysaccharide and the odor controlling agent maybe distributed homogeneously or non homogeneously on the whole surfaceof the desired layer or layers, or on one or several area of the surfacelayer/layers to which it is positioned (e.g. central area and/orsurrounding area like the edges of a layer of the absorbent article) ormixtures thereof.

The cationic polysaccharide and the odor-controlling agent may bepositioned together in the same location (e.g., layer) or separately indifferent locations/layers. For example in one embodiment herein theodor controlling agent (e.g., zeolite and/or cyclodextrin and/or EDTA)is positioned such that at least a portion of the fluid/exudate comesinto contact with it before the cationic polysaccharide, preferablychitosan material. Preferably the odor controlling agent is located inthe core towards the topsheet or located in the topsheet itself(preferably the secondary topsheet) and the cationic polysaccharide islocated further away from the topsheet than the odor controlling agent.In one embodiment of the present invention, the odor-controlling agentis positioned in at least one of the topsheet layers and the cationicpolysaccharide, typically chitosan material, is positioned in the core.In another embodiment herein the odor controlling agent and the cationicpolysaccharide are both located in the core, but the cationicpolysaccharide is located beneath the odor-controlling agent, typicallythe cationic polysaccharide is located towards the backsheet. In anotherembodiment the odor controlling agent is located in the absorbent coreand the cationic polysaccharide in the backsheet itself (preferably thesecondary backsheet).

In a preferred embodiment herein, wherein an absorbent gelling materialis present, the absorbent gelling material and the odor controllingagent are positioned such that at least a portion of the bodilyfluid/exudate comes into contact with said absorbent gelling materialand odor controlling agent before the cationic polysaccharide. In ahighly preferred embodiment herein the absorbent gelling material andodor controlling agent are located in the absorbent core and thecationic polysaccharide, typically chitosan material, is located too inthe absorbent core but further away from the topsheet than the absorbentgelling material and odor controlling agent. In an execution wherein thecore is made of laminate of two layers of cellulose tissue, theabsorbent gelling material and the odor controlling agent areincorporated between these two layers and the polysaccharide is appliedon the layer positioned in proximity to the backsheet, preferably on theinner side of this layer so as to be in close proximity to the absorbentgelling material and odor controlling agent. Such executions areparticularly beneficial for combining optimum odor control propertieswith optimum fluid handling, i.e., optimum odor and fluid absorption andretention without any leakage through or rewetting occurrence. Thecationic properties of the cationic polysaccharides will be boosted dueto the close proximity to the absorbent gelling material. Furthermorethe cationic polysaccharide due to its gelifying properties will havethe tendency to form a so-called impermeable layer towards the backsheetthereby preventing any leakage through.

The cationic polysaccharides and odor controlling agents as well as theoptional absorbent gelling material if present may be incorporated as apowder, a granulate or can be sprayed in the form of for example apolysaccharide-containing solution and/or odor controllingagent-containing solution within the absorbent article. When used in agranulate or particulate form the cationic polysaccharides (e.g.,chitosan material) and odor controlling agents as well as the optionalabsorbent gelling materials may be granulated separately and then mixedtogether or granulated together.

Typical disposable absorbent articles according to the preferredembodiments of the present invention are those as described hereinafter:

Absorbent Core

According to the present invention, the absorbent can include thefollowing components: (a) an optional primary fluid distribution layerpreferably together with a secondary optional fluid distribution layer;(b) a fluid storage layer; (c) an optional fibrous (“dusting”) layerunderlying the storage layer; and (d) other optional components.According to the present invention the absorbent may have any thicknessdepending on the end use envisioned.

a Primary/Secondary Fluid Distribution Layer

One optional component of the absorbent according to the presentinvention is a primary fluid distribution layer and a secondary fluiddistribution layer. The primary distribution layer typically underliesthe topsheet and is in fluid communication therewith. The topsheettransfers the acquired fluid to this primary distribution layer forultimate distribution to the storage layer. This transfer of fluidthrough the primary distribution layer occurs not only in the thickness,but also along the length and width directions of the absorbent product.The also optional but preferred secondary distribution layer typicallyunderlies the primary distribution layer and is in fluid communicationtherewith. The purpose of this secondary distribution layer is toreadily acquire fluid from the primary distribution layer and transferit rapidly to the underlying storage layer. This helps the fluidcapacity of the underlying storage layer to be fully utilized. The fluiddistribution layers can be comprised of any material typical for suchdistribution layers. In particular fibrous layers maintain thecapillaries between fibers even when wet are useful as distributionlayers.

b Fluid Storage Layer

Positioned in fluid communication with, and typically underlying theprimary or secondary distribution layers, is a fluid storage layer. Thefluid storage layer can comprise the cationic polysaccharides andoptional absorbent gelling material. It preferably comprises thecationic polysaccharides and optional absorbent gelling materials incombination with suitable carriers.

Suitable carriers include materials, which are conventionally utilizedin absorbent structures such as natural, modified or synthetic fibers,particularly modified or non-modified cellulose fibers, in the form offluff and/or tissues. Most preferred are tissue or tissue laminates inthe context of sanitary napkins and panty liners.

An embodiment of the absorbent structure made according to the presentinvention may comprise multiple layers comprises a double layer tissuelaminate formed by folding the tissue onto itself. These layers can bejoined to each other for example by adhesive or by mechanicalinterlocking or by hydrogen bridge bands. The cationic polysaccharides(together with the odor controlling agents) and optional absorbentgelling materials can be comprised between the layers.

Modified cellulose fibers such as the stiffened cellulose fibers canalso be used. Synthetic fibers can also be used and include those madeof cellulose acetate, polyvinyl fluoride, polyvinylidene chloride,acrylics (such as Orlon), polyvinyl acetate, non-soluble polyvinylalcohol, polyethylene, polypropylene, polyamides (such as nylon),polyesters, bicomponent fibers, tricomponent fibers, mixtures thereofand the like. Preferably, the fiber surfaces are hydrophilic or aretreated to be hydrophilic. The storage layer can also include fillermaterials, such as Perlite, diatomaceous earth, Vermiculite, etc., toimprove liquid retention.

If the cationic polysaccharides and optional absorbent gelling materialsare dispersed non-homogeneously in a carrier, the storage layer cannevertheless be locally homogenous, i.e. have a distribution gradient inone or several directions within the dimensions of the storage layer.Non-homogeneous distribution can also refer to laminates of carriersenclosing cationic polysaccharides and optional absorbent gellingmaterials partially or fully.

c Optional Fibrous (“Dusting”) Layer

An optional component for inclusion in the absorbent core according tothe present invention is a fibrous layer adjacent to, and typicallyunderlying the storage layer. This underlying fibrous layer is typicallyreferred to as a “dusting” layer since it provides a substrate on whichto deposit absorbent gelling material in the storage layer duringmanufacture of the absorbent core. Indeed, in those instances where theabsorbent gelling material is in the form of macro structures such asfibers, sheets or strips, this fibrous “dusting” layer need not beincluded. However, this “dusting” layer provides some additionalfluid-handling capabilities such as rapid wicking of fluid along thelength of the pad.

d Other Optional Components of the absorbent structure

The absorbent core according to the present invention can include otheroptional components normally present in absorbent webs. For example, areinforcing scrim can be positioned within the respective layers, orbetween the respective layers, of the absorbent core. Such reinforcingscrims should be of such configuration as to not form interfacialbarriers to fluid transfer. Given the structural integrity that usuallyoccurs as a result of thermal bonding, reinforcing scrims are usuallynot required for thermally bonded absorbent structures.

The Topsheet

According to the present invention the absorbent article comprises as anessential component a topsheet. The topsheet may comprise a single layeror a multiplicity of layers. In a preferred embodiment the topsheetcomprises a first layer, which provides the user-facing surface of thetopsheet and a second layer (also called secondary topsheet) between thefirst layer and the absorbent structure/core.

The topsheet as a whole and hence each layer individually needs to becompliant, soft feeling, and non-irritating to the wearer's skin. Italso can have elastic characteristics allowing it to be stretched in oneor two directions. According to the present invention the topsheet maybe formed from any of the materials available for this purpose and knownin the art, such as woven and non-woven fabrics and films.

In a preferred embodiment of the present invention at least one of thelayers, preferably the upper layer, of the topsheet comprises ahydrophobic, liquid permeable apertured polymeric film. Preferably, theupper layer is provided by a film material having apertures, which areprovided to facilitate liquid transport from the wearer-facing surfacetowards the absorbent structure. If present the lower layer preferablycomprises a non-woven layer, an apertured formed film or an air laidtissue.

The term apertured polymeric topsheet as used herein refers to topsheetscomprising at least one layer or a multiplicity of layers wherein atleast one layer is formed from a continuous or uninterrupted filmmaterial wherein apertures are created. It has been surprisinglydiscovered that apertured polymeric film topsheets yield significantlybetter odor control than other types of topsheets such as for examplethermal bonded nonwoven materials.

In general the apertured polymeric topsheet of the present invention iscompliant, soft feeling, and non-irritating to the wearer's skin.Further, the topsheet is fluid pervious permitting fluids (e.g., mensesand/or urine) to readily penetrate through its thickness. Suitableapertured polymeric film topsheets for use herein include polymericapertured formed films, thermoplastic films, apertured plastic films,and hydroformed thermoplastic films; porous foams; net-like reticulatedfoams and thermoplastic films; and thermoplastic scrims.

Preferred topsheets for use in the present invention are selected fromapertured formed film topsheets. Apertured formed films are especiallypreferred for the topsheet because they are pervious to body exudatesand yet non-absorbent and have a reduced tendency to allow fluids topass back through and rewet the wearer's skin. Thus, the surface of theformed film that is in contact with the body remains dry; therebyreducing body soiling and creating a more comfortable feel for thewearer. Suitable formed films are described in U.S. Pat. No. 3,929,135(Thompson), issued Dec. 30, 1975; U.S. Pat. No. 4,324,246 (Mullane, etal.), issued Apr. 13, 1982; U.S. Pat. No. 4,342,314 (Radel. et al.),issued Aug. 3, 1982; U.S. Pat. No. 4,463,045 (Ahr et al.), issued Jul.31, 1984; and U.S. Pat. No. 5,006,394 (Baird), issued Apr. 9, 1991. Eachof these patents are incorporated herein by reference. Particularlypreferred microapertured formed film topsheets are disclosed in U.S.Pat. No. 4,609,518 (Curro et al), issue Sep. 2, 1986 and U.S. Pat. No.4,629,643 (Curro et al), issued Dec. 16, 1986, which are incorporated byreference. The preferred topsheet for the present invention is theformed film described in one or more of the above patents and marketedon sanitary napkins by The Procter & Gamble Company of Cincinnati, Ohioas “DRI-WEAVE.”

Suitable topsheets in the field of three-dimensional formed film aredescribed in EP 0 018 020 and EP 0 059 506. Especially preferred in athree dimensional formed polymeric topsheet having openings in the shapeof regular pentagons which are regularly spaced and have an opening of0.41 square millimeter. The openings are spaced 0.37 square millimetersapart transversely and 0.25 millimeters longitudinally. This topsheethas an initial opening (preforming) thickness of about 25 m a final(post forming) thickness of about 0.53 mm and an open area of from 25%to about 40%.

Another formed film topsheet which is especially preferred is one havingopenings of two shapes; regular pentagons having an area of about 0.21square millimeters and an irregular hexagon having an area of 1.78square millimeters. The openings are distributed so that the distancebetween the sides of the figures is about 0.37 mm to about 0.42 mm. Thepreforming and post forming film thickness are respectively 0.25 and0.43 mm. This film has an open area of about 33.7%. Both films are madeaccording to the teachings of the above-mentioned patents.

A third form suitable topsheet comprises two separate perforatedpolymeric films superimposed one on the other.

The body surface of the formed film topsheet of the present inventionmay also be hydrophilic so as to help liquid to transfer through thetopsheet faster than if the body surface was not hydrophilic. In thismanner the likelihood that menstrual fluid will flow off the topsheetrather than flowing into and being absorbed by the absorbent structureis diminished. In a preferred embodiment, surfactant is incorporatedinto the polymeric materials of the formed film topsheet such as isdescribed in U.S. patent application Ser. No. 07/794,745, “AbsorbentArticle Having A Nonwoven and Apertured Film Coversheet” filed on Nov.19, 1991 by Aziz, et al., which is incorporated by reference.Alternatively, the body surface of the topsheet can be made hydrophilicby treating it with a surfactant such as is described in the abovereferenced U.S. Pat. No. 4,950,254, incorporated herein by reference.

The Backsheet

The backsheet primarily prevents the extrudes absorbed and contained inthe absorbent structure from wetting articles that contact the absorbentproduct such as underpants, pants, pyjamas and undergarments. Thebacksheet is preferably impervious to liquids (e.g. menses and/or urine)and is preferably manufactured from a thin plastic film, although otherflexible liquid impervious materials can also be used. As used herein,the term “flexible” refers to materials that are compliant and willreadily conform to the general shape and contours of the human body. Thebacksheet also can have elastic characteristics allowing it to stretchin one or two directions. In a preferred embodiment the backsheetcomprises a first layer, which provides the garment-facing surface ofthe backsheet and a second layer (also called secondary backsheet)between the first layer and the absorbent structure/core.

The backsheet typically extends across the whole of the absorbentstructure and can extend into and form part of or all of the preferredside flaps, side wrapping elements or wings.

The backsheet can comprise a woven or nonwoven material, polymeric filmssuch as thermoplastic films of polyethylene or polypropylene, orcomposite materials such as a film-coated nonwoven material. Preferably,the backsheet is a polyethylene film typically having a thickness offrom about 0.012 mm (0.5 mil) to about 0.051 mm (2.0 mil).

Exemplary polyethylene films are manufactured by Clopay Corporation ofCincinnati, Ohio, under the designation P18-0401 and by EthylCorporation, Visqueen Division, of Terre Haute, Ind., under thedesignation XP-39385. The backsheet is preferably embossed and/or mattfinished to provide a more cloth like appearance. Further, the backsheetcan permit vapors to escape from the absorbent structure, i.e. bebreathable, while still preventing exudates from passing through thebacksheet. Also breathable backsheets comprising several layers, e.g.film plus non-woven structures, can be used.

Suitable breathable backsheets for use herein include all breathablebacksheets known in the art. In principle there are two types ofbreathable backsheets, single layer breathable backsheets that arebreathable and impervious to liquids and backsheets having at least twolayers, which in combination provide both breathability and liquidimperviousness.

Suitable single layer breathable backsheets for use herein include thosedescribed for example in GB A 2184 389, GB A 2184 390, GB A 2184 391,U.S. Pat. No. 4,591,523, U.S. Pat. No. 3,989,867 U.S. Pat. No. 3,156,242and European Patent Application number 95120653.1.

Suitable dual or multi layer breathable backsheets for use hereininclude those exemplified in U.S. Pat. No. 3,881,489, U.S. Pat. No.4,341,216, U.S. Pat. No. 4,713,068, U.S. Pat. No. 4,818,600, EPO 203821, EPO 710 471, EPO 710 472, European Patent Application numbers95120647.3, 95120652.3, 95120653.1 and 96830097.0.

Particularly preferred are backsheets meeting the requirements asdefined in European Patent Application number 96830343.8 and morepreferably wherein the absorbent article also meets the requirements asdescribed therein.

According to the present invention the breathable backsheet comprises atleast one, preferably at least two water vapor permeable layers.Suitable water vapor permeable layers include 2 dimensional, planarmicro and macro-porous films, monolithic films, macroscopically expandedfilms and formed apertured films. According to the present invention theapertures in said layer may be of any configuration, but are preferablyspherical or oblong. The apertures may also be of varying dimensions. Ina preferred embodiment the apertures are preferably evenly distributedacross the entire surface of the layer, however layers having onlycertain regions of the surface having apertures are also envisioned.

2 dimensional planar films as used herein have apertures having anaverage diameter of from 5 micrometers to 200 micrometers. Typically,2-dimensional planar micro porous films suitable for use herein haveapertures having average diameters of from 150 micrometers to 5micrometers, preferably from 120, micrometers to 10 micrometers, mostpreferably from 90 micrometers to 15 micrometers. Typical 2 dimensionalplanar macroporous films have apertures having average diameters of from200 micrometers to 90 micrometers. Macroscopically expanded films andformed apertured films suitable for use herein typically have apertureshaving diameters from 100 micrometers to 500 micrometers. Embodimentsaccording to the present invention wherein the backsheet comprises amacroscopically expanded film or an apertured formed film, the backsheetwill typically have an open area of more than 5%, preferably from 10% to35% of the total backsheet surface area.

Suitable 2 dimensional planar layers of the backsheet may be made of anymaterial known in the art, but are preferably manufactured from commonlyavailable polymeric materials. Suitable materials are for exampleGORE-TEX (TM) or Sympatex (TM) type materials well known in the art fortheir application in so-called breathable clothing. Other suitablematerials include XMP-1001 of Minnesota Mining and ManufacturingCompany, St. Paul, Minn., USA. As used herein the term 2 dimensionalplanar layer refers to layers having a depth of less than 1 mm,preferably less than 0.5 mm, wherein the apertures have an averageuniform diameter along their length and which do not protrude out of theplane of the layer. The apertured materials for use as a backsheet inthe present invention may be produced using any of the methods known inthe art such as described in EPO 293 482 and the references therein. Inaddition, the dimensions of the apertures produced by this method may beincreased by applying a force across the plane of the backsheet layer(i.e. stretching the layer).

Suitable apertured formed films include films, which have discreteapertures, which extend beyond the horizontal plane of thegarment-facing surface of the layer towards the core thereby formingprotuberances. The protuberances have an orifice located at theirterminating ends. Preferably said protuberances are of a funnel shape,similar to those described in U.S. Pat. No. 3, 929,135. The apertureslocated within the plane and the orifices located at the terminating endof protuberance themselves maybe circular or non circular, provided thecross sectional dimension or area of the orifice at the termination ofthe protuberance is smaller than the cross sectional dimension or areaof the aperture located within the garment facing surface of the layer.Preferably said apertured preformed films are unidirectional such thatthey have at least substantially, if not complete one directional fluidtransport towards the core. Suitable macroscopically expanded films foruse herein include films as described in for example in U.S. Pat. No.637,819 and U.S. Pat. No. 4,591,523.

Suitable macroscopically expanded films for use herein include films asdescribed in for example U.S. Pat. No. 4,637,819 and U.S. Pat. No.4,591,523.

Suitable monolithic films include Hytrel™, available from DuPontCorporation, USA, and other such materials as described in Index 93Congress, Session 7A “Adding value to Nonwovens”, J-C. Cardinal and Y.Trouilhet, DuPont de Nemours International S.A., Switzerland.

According to the present invention the backsheet may comprise inaddition to said water vapor permeable layer additional backsheetlayers. Said additional layers may be located on either side of saidwater vapor permeable layer of the backsheet. The additional layers maybe of any material, such as fibrous layers or additional water vaporpermeable layers as described herein above.

Odor Control Test

The odor reduction is measured by for example an in vitro sniff test. Invitro sniff test consists in analyzing by expert graders the odorassociated with articles comprising the ingredients to be tested(including references articles) when contacted with an odorouscomponents-containing solution

The expert graders express their judgment about (un)pleasantness of theodor using a (un)pleasantness scale, typically from −10 (highest levelof unpleasantness) to 5 (most pleasant). With this procedure, eachgrader compares MU (Unpleasantness) in the test session. The relative MUodor values from different products are assigned numbers. For example,in a test session, a sample that is perceived to be twice as strong asanother is assigned twice as large a number. One that is perceived to beone-tenth as strong as another is assigned a number one-tenth as large,etc. In each test session, zero is used to designate neutral hedonicity,and + and − numbers are assigned in ratio proportion to the relativepleasantness and unpleasantness of the odor.

Surprisingly in vitro in-house sniff tests conducted by using anin-house odorous components-containing solution reproducing theessential malodorous characteristics of menses showed synergistic odorreduction when comparing chitosan (e.g. chitosonium pyrrolidonecarboxylate (Kytamer®) together with an odor controlling agent accordingto the present invention (e.g., zeolite A, Wessalith CS, available fromDegussa AG, or ethylenediamine tetracetate (BASF) or hydroxypropylbeta-cyclodextrin (Fluka)) to each of these ingredients taken alone atthe same total level of active. Indeed the % of unpleasantness reductionobtained for the mixture was higher than the % of unpleasantnessreduction obtained for each of the two ingredients used alone at thesame total level of active. The Unpleasantness values, for each sample,were obtained as a mean of at least 15 observations (3 products, 5graders). These results were statistically significant.

Alternatively the odor reduction can also be measured with in vivo snifftests as described in patent applications, EP-A-811387 or WO97/4619 1,herein incorporated by reference. The present invention is furtherillustrated by the following examples.

EXAMPLES Example A

The feminine pads used in the following examples were Always (Always isa registered Trade Mark) as sold by the Procter & Gamble Company.

Each feminine pad was opened by cutting the wrap around the perforatedcoverstock at its bottom face approximately along a longitudinal edge ofthe release paper, which covers the external adhesive layer. The side ofthe absorbent fibrous core was then exposed by slightly shifting thewater impermeable plastic bottom layer and subsequently, the fibrouscore was split into two halves, each having approximately the samethickness, along a plane, which is parallel to the plane of the paditself. Chitosan material and odor controlling agent were homogeneouslydistributed between the two fibrous layers.

The water impermeable inner backsheet was then put back into itsoriginal position and the wrap around perforated coverstock was sealedalong the cut by means of e.g. a double-sided adhesive tape.

The chitosan powder material used was 0.2 g of chitosonium pyrrolidonecarboxylate, commercially available from Amerchol Corporation, Edison,N.J. under the name Kytamer® PC.

The odor-controlling agent used was 0.3 g of Zeolite A, Wessalith CS,available from Degussa AG.

Example B

Other pads were prepared by following the method in Example A exceptthat the odor-controlling agent used was cyclodextrin instead ofzeolite. The cyclodextrin used was 0.1 g of hydroxypropylbeta-cyclodextrin commercially available from Fluka.

Example C

Other pads were prepared by following the method in Example A exceptthat the odor-controlling agent used was a chelating agent instead ofzeolite. The chelating agent used was 0.1 g of ethylenediaminetetracetate commercially available from BASF AG.

Examples D, E and F

Other pads were prepared by following the method in respectivelyExamples A, B, and C except that an absorbent gelling material (AGM) washomogeneously distributed between the two fibrous layer beside thechitosan material and odor controlling agent used respectively inExamples A, B and C.

The AGM used was 0.4 g of cross-linked sodium polyacrylate Xz 9589001,available from Dow Chemicals.

Examples G, H and I

Other pads were prepared by following the method in respectivelyExamples A, B and C except that after having split the fibrous core intotwo halves, an absorbent gelling material (AGM) and the odor controllingagent as defined in respectively Examples A, B and C, were respectivelyhomogeneously distributed between the two halve fibrous layers and thechitosan material was homogeneously distributed onto the lower halvefibrous layer (i.e., the one intended to be closer to the backsheet ofthe pad once reconstituted). Actually a solution of chitosan materialwas prepared and homogeneously sprayed onto the inner side of the lowerhalve fibrous layer.

The chitosan solution was prepared by solubilizing 1 g of chitosoniumpyrrolidone carboxylate commercially available from Amerchol Corporationunder the name Kytamer® PC in 100 g of distilled water and stirring at40° C. over 1 night. 10 g of the prepared solution was sprayed onto thelower halve of the fibrous layer (i.e., 0.1 g of chitosan per pad) AGMused was 0.4 g of cross-linked sodium polyacrylate, commerciallyavailable from Dow Chemicals (code:XZ 9589001).

The odor controlling agents used (type and amount) were the onesrespectively defined in Examples A, B and C.

Accordingly various pads were made respectively corresponding toExamples G, H and I with different odor controlling agents,corresponding respectively to the odor controlling agents used inExamples A, B and C described herein above.

Example J

The feminine pantiliner used in the following examples is a modifiedpanty liner based on Always “Alldays Duo Active” manufactured by Procter& Gamble, Germany. The topsheet is a film/non woven composite {filmsupplier code BPC 5105 CPM BP Chemical Germany, non-woven supplier codeARBO TB/BI Mequinenza Spain}. The core material is a tissue laminate(13.2 cm×4.0 cm) composed of a 2 layers of air laid tissue of 55 g/m²basis weight {available from Unikay Italy under the supplier code Unikay303 LF}. Between the two tissue layers the laminate contains chitosanmaterial together with an odor-controlling agent.

The backsheet comprises two layers a first layer and a second layer. Thefirst layer is in contact with the absorbent tissue and the secondlayer. The second layer is in contact with the first layer and theundergarment of the wearer. The first layer is a formed apertured film(CPT) made of Low Density PE {supplied by Tredegar Film Products B. V.Holland under the manufacturing code X-1522}. The second layer iscomposed of a nonwoven laminate {13 MB/16 SB manufactured by CorovinGmbH in Germany under the trade name MD 2005}. The nonwoven laminate iscomposed of 16 g/m² spun bond and 13 g/m² meltblown. Each backsheetlayer is joined over the full surface by an extensively overlappedspiral glue application at a basis weight of approximately 8 g/m². Theglue utilized for attachment of both backsheet layers was supplied bySAVARE' SpA. Italy (under the material code PM 17).

The chitosan material used was 0.2 g of chitosonium pyrrolidonecarboxylate, commercially available from Amerchol Corporation, Edison,N.J. under the name Kytamer® PC.

The odor controlling agent used was either 0.3 g of Zeolite A, WessalithCS, available from Degussa AG, or 0.1 g of hydroxypropylbeta-cyclodextrin commercially available from Fluka, or 0.1 g ofethylenediamine tetracetate (EDTA) commercially available from BASF AG.

Other panty liners can be made starting from the ones exemplified inExample J above except that AGM is incorporated on top of the chitosanmaterial and odor-controlling agent. Indeed the 3 classes of ingredientswere homogeneously mixed together to obtain a powder that washomogeneously distributed between the two layers of the laminate. AGMused was 0.4 g of cross-linked sodium polyacrylate, commerciallyavailable from Dow Chemicals (code:XZ 9589001).

All the above exemplified pads and pantiliners delivered outstandingodor control properties towards malodorous compounds associated withbodily fluids.

1. A disposable absorbent article comprising a liquid pervious topsheet,a backsheet and an absorbent core intermediate to said backsheet andsaid topsheet; said absorbent core comprising an odour control systemfor controlling odours comprising a cationic polysaccharide togetherwith an odor controlling agent; wherein said cationic polysaccharide isan aminopolysaccharide selected from the group consisting of chitosan,chitosan salt, chitosans that comprise carboxymethyl, memylpyrrolldinoneor glycol pendant groups on a glucan chain, crosslinked chitosan andmixtures thereof.
 2. An article according to claim 1 wherein saidchitosan has a degree of deacetylation of more than 75%.
 3. An articleaccording to claim 1 wherein the cationic polysaccharide is selectedfrom the group consisting of a chitosan salt of citric acid, formicacid, acetic acid, N-acetylglycine, acetylsalicylic acid, fumaric acid,glycolic acid, iminodiacetic acid, itaconic acid, lactic acid, maleicacid, malic acid, nicotinic acid, salicylic acid, succinamic acid,succinic acid, ascorbic acid, aspartic acid, glutamic acid, glutaricacid, malonic acid, pyruvic acid, sulfonyldiacetic acid, benzoic acid,epoxysuccinic acid, adipic acid, thiodiacetic acid, thioglycolic acid,alanine, valine, leucine, isoleucine, prolinephenylalanine, triptofane,metionine, glycine, serine, cysteine, tyrosine, asparagine, glutamine,lysine, arginine, histidine, hydroxyproline, pyrrolidone carboxylicacid, chitosonium pyrrolidone carboxylate and mixtures thereof.
 4. Anarticle according to claim 1 which comprises from about 0.5 gm⁻² toabout 500 gm⁻² of cationic polysaccharide.
 5. An article according toclaim 1 wherein the odor controlling agent is a chelating agent and/oran odor absorbent agent.
 6. An article according to claim 5 wherein saidodor controlling agent is an odor absorbent agent selected from thegroup consisting of zeolites, carbons, diatomaceous earth, starches,cyclodextrin, kieselguhr, clays, ion exchange resins and combinationthereof and preferably is zeolite, aipha-cyclodextrin,beta-cyclodextrin, gamma-cyclodextrin or a combination thereof.
 7. Anarticle according to claim 5 wherein the odor controlling agent is achelating agent selected from the group consisting of phosphonatechelating agents, amino phosphonate chelating agents,polyfunctionally-substituted aromatic chelating agents, animocarboxylate chelating agents, ethylene diamine N,N′-disuccinic acid,aspartic acid, glutamic acid, malonic acid, glycine and mixturesthereof.
 8. An article according to claim 7 wherein the chelating agentis selected from the group consisting of ethylene diamine tetracetate,-triacetate, -diacetate, and -monoacetate, ethylenediamineN,N,-disuccinic acid, ethylenediamine penta methylene phosphonic acid,ethylenediamine tetra methylene phosphonic acid and mixtures thereof. 9.An article according to claim 1 which comprises from about 1 to about600 gm⁻² of the odor controlling agent.
 10. An article according toclaim 1 further comprising an absorbent gelling material.
 11. An articleaccording to claim 5 further comprising an absorbent gelling material.12. An article according to claim 10, wherein the absorbent gellingmaterial is present at a level from about 5 gm⁻² to about 250 gm⁻².